Presently internal combustion engines particularly 4 cycle engines typically utilize separate intake and exhaust valves and separate intake and exhaust runners for each valve. In other words each intake valve or set of intake valves is supplied by an individual intake runner via the intake manifold. Similarly each exhaust valve and/or each set of exhaust valves typically is connected to a separate and individual exhaust runner which leads into the exhaust manifold.
With improvements in the ability to very specifically mix quantities of air and fuel together either through fuel injection techniques and/or direct injection into each individual cylinder it is now possible to utilize a single integral intake runner in an internal combustion engine head.